Method and apparatus for inspecting display device

ABSTRACT

A method for inspecting a display device (which includes a pixel electrode and a touch sensor overlapping the pixel electrode) includes: adjusting an impedance value of a variable impedance circuit of an inspection apparatus according to a model of the display device; driving a power source generator of the inspection apparatus; supplying a pixel voltage to the pixel electrode through an output terminal connected to the variable impedance circuit; driving the touch sensor; and detecting a defect related to the pixel electrode based on sensing signals output from the touch sensor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2021-0125076, filed Sep. 17, 2021, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

One or more embodiments relate to a method and apparatus for inspectinga display device.

Discussion

In recent years, interest in information displays has increased.Accordingly, research and development on display devices have beencontinuously conducted, such in the realm of detecting defects toimprove display quality.

The above information disclosed in this section is only forunderstanding the background of the inventive concepts, and, therefore,may contain information that does not form prior art.

SUMMARY

One or more embodiments provide a method for inspecting a display deviceand capable of detecting a defect related to a pixel electrode of thedisplay device including a touch sensor

One or more embodiments provide an apparatus for inspecting a displaydevice and capable of detecting a defect related to a pixel electrode ofthe display device including a touch sensor.

Additional aspects will be set forth in the detailed description whichfollows, and, in part, will be apparent from the disclosure, or may belearned by practice of the inventive concepts.

According to an embodiment, a method for inspecting a display device(which includes a pixel electrode and a touch sensor overlapping thepixel electrode) includes: adjusting an impedance value of a variableimpedance circuit of an inspection apparatus according to a model of thedisplay device; driving a power source generator of the inspectionapparatus; supplying a pixel voltage to the pixel electrode through anoutput terminal connected to the variable impedance circuit; driving thetouch sensor; and detecting a defect related to the pixel electrodebased on sensing signals output from the touch sensor.

According to an embodiment, an apparatus for inspecting a display deviceincludes a power source generator and a variable impedance circuit. Thepower source generator is configured to generate a pixel voltage of thedisplay device. The variable impedance circuit is electrically connectedto an output terminal of the power source generator. The variableimpedance circuit includes a variable resistance circuit and a variablecapacitor circuit. The variable resistance circuit is electricallyconnected between the output terminal of the power source generator andan output terminal of the variable impedance circuit. The variablecapacitor circuit is electrically connected between the output terminalof the power source generator and a reference voltage source.

The foregoing general description and the following detailed descriptionare illustrative and explanatory and are intended to provide furtherexplanation of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the inventive concepts, and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinventive concepts, and, together with the description, serve to explainprinciples of the inventive concepts.

FIG. 1 is a block diagram illustrating a display device according to anembodiment.

FIG. 2 is a cross-sectional view schematically illustrating a panel unitof the display device according to an embodiment.

FIG. 3 is a plan view illustrating a display panel according to anembodiment.

FIG. 4 is a circuit diagram illustrating a pixel according to anembodiment.

FIG. 5 is a plan view illustrating a touch sensor according to anembodiment.

FIG. 6 is a cross-sectional view illustrating the panel unit of thedisplay device according to an embodiment.

FIG. 7 is a cross-sectional view schematically illustrating anarrangement structure of a second pixel electrode of a display panel andsensor electrodes of the touch sensor according to an embodiment.

FIG. 8 is a diagram illustrating the display device centered on thetouch sensor according to an embodiment.

FIG. 9 is a graph illustrating a sensing signal generated by a mutualcapacitance of the touch sensor, a noise signal generated by the secondpixel electrode, and a sensing signal input to a sensing circuitaccording to an embodiment.

FIG. 10 is a diagram illustrating the display device including a firsttype of defect in relation to the second pixel electrode.

FIG. 11 is a diagram illustrating the panel unit including a second typeof defect in relation to the second pixel electrode.

FIG. 12 is a diagram illustrating the panel unit including a third typeof defect in relation to the second pixel electrode.

FIG. 13 is a diagram illustrating an inspection apparatus of the displaydevice according to an embodiment.

FIG. 14 is a graph illustrating capacitance values of sensing signalsoutput from a touch sensor of the display device according to anembodiment.

FIG. 15 is a flowchart illustrating a method of inspecting a displaydevice according to an embodiment.

FIG. 16 is a flowchart illustrating a method of generating referencedata according to an embodiment.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various embodiments. As used herein, the terms“embodiments” and “implementations” may be used interchangeably and arenon-limiting examples employing one or more of the inventive conceptsdisclosed herein. It is apparent, however, that various embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form to avoid unnecessarily obscuringvarious embodiments. Further, various embodiments may be different, butdo not have to be exclusive. For example, specific shapes,configurations, and characteristics of an embodiment may be used orimplemented in another embodiment without departing from the inventiveconcepts.

Unless otherwise specified, the illustrated embodiments are to beunderstood as providing example features of varying detail of someembodiments. Therefore, unless otherwise specified, the features,components, modules, layers, films, panels, regions, aspects, etc.(hereinafter individually or collectively referred to as an “element” or“elements”), of the various illustrations may be otherwise combined,separated, interchanged, and/or rearranged without departing from theinventive concepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. As such, thesizes and relative sizes of the respective elements are not necessarilylimited to the sizes and relative sizes shown in the drawings. When anembodiment may be implemented differently, a specific process order maybe performed differently from the described order. For example, twoconsecutively described processes may be performed substantially at thesame time or performed in an order opposite to the described order.Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element, it may be directly on,connected to, or coupled to the other element or intervening elementsmay be present. When, however, an element is referred to as being“directly on,” “directly connected to,” or “directly coupled to” anotherelement, there are no intervening elements present. Other terms and/orphrases used to describe a relationship between elements should beinterpreted in a like fashion, e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” “on” versus “directlyon,” etc. Further, the term “connected” may refer to physical,electrical, and/or fluid connection. In addition, the DR1-axis, theDR2-axis, and the DR3-axis are not limited to three axes of arectangular coordinate system, and may be interpreted in a broadersense. For example, the DR1-axis, the DR2-axis, and the DR3-axis may beperpendicular to one another, or may represent different directions thatare not perpendicular to one another. For the purposes of thisdisclosure, “at least one of X, Y, and Z” and “at least one selectedfrom the group consisting of X, Y, and Z” may be construed as X only, Yonly, Z only, or any combination of two or more of X, Y, and Z, such as,for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Although the terms “first,” “second,” etc. may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms are used to distinguish one element from anotherelement. Thus, a first element discussed below could be termed a secondelement without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one element's relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the term“below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing someembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various embodiments are described herein with reference to sectionalviews, isometric views, perspective views, plan views, and/or explodedillustrations that are schematic illustrations of idealized embodimentsand/or intermediate structures. As such, variations from the shapes ofthe illustrations as a result of, for example, manufacturing techniquesand/or tolerances, are to be expected. Thus, embodiments disclosedherein should not be construed as limited to the particular illustratedshapes of regions, but are to include deviations in shapes that resultfrom, for instance, manufacturing. To this end, regions illustrated inthe drawings may be schematic in nature and shapes of these regions maynot reflect the actual shapes of regions of a device, and, as such, arenot intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and will not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

As customary in the field, some embodiments are described andillustrated in the accompanying drawings in terms of functional blocks,units, and/or modules. Those skilled in the art will appreciate thatthese blocks, units, and/or modules are physically implemented byelectronic (or optical) circuits, such as logic circuits, discretecomponents, microprocessors, hard-wired circuits, memory elements,wiring connections, and the like, which may be formed usingsemiconductor-based fabrication techniques or other manufacturingtechnologies. In the case of the blocks, units, and/or modules beingimplemented by microprocessors or other similar hardware, they may beprogrammed and controlled using software (e.g., microcode) to performvarious functions discussed herein and may optionally be driven byfirmware and/or software. It is also contemplated that each block, unit,and/or module may be implemented by dedicated hardware, or as acombination of dedicated hardware to perform some functions and aprocessor (e.g., one or more programmed microprocessors and associatedcircuitry) to perform other functions. Also, each block, unit, and/ormodule of some embodiments may be physically separated into two or moreinteracting and discrete blocks, units, and/or modules without departingfrom the inventive concepts. Further, the blocks, units, and/or modulesof some embodiments may be physically combined into more complex blocks,units, and/or modules without departing from the inventive concepts.

Hereinafter, various embodiments will be explained in detail withreference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a display device 10 according toan embodiment. FIG. 2 is a cross-sectional view schematicallyillustrating a panel unit 100 of the display device 10 according to anembodiment.

Referring to FIGS. 1 and 2 , the display device 10 according to anembodiment may include the panel unit (or panel) 100 and a drivingcircuit unit (or driving circuit) 200. The driving circuit unit 200 maybe electrically connected to the panel unit 100, and may supply powersource voltages and driving signals for driving the panel unit 100 tothe panel unit 100. Also, the driving circuit unit 200 may receivesensing signals from the panel unit 100 and may detect a touch inputgenerated from the panel unit 100 based on the sensing signals.

The panel unit 100 may include a display panel 110 and a touch sensor120 (or a sensor unit of the touch sensor 120). The display panel 110and the touch sensor 120 may overlap each other. For example, the touchsensor 120 may be provided on the display panel 110, such as provideddirectly on the display panel 110.

The panel unit 100 may further include a protective layer 130 positionedon (or as) the uppermost layer. For example, the protective layer 130may be provided on the touch sensor 120.

In an embodiment, the panel unit 100 may be a panel unit of a flexibledisplay device having flexibility such that at least a portion of theflexible display device can be folded, bent, twisted, rolled, orotherwise flexed. To increase flexibility, the panel unit 100 may beprovided with a thin thickness.

In an embodiment, the display panel 110 and the touch sensor 120 may beintegrally formed and/or provided. For example, the touch sensor 120 maybe directly formed on the display panel 110. For instance, the touchsensor 120 may be formed in a continuous process with the display panel110 such that an adhesive layer is not formed between the touch sensor120 and the display panel 110. When the touch sensor 120 is integrallyformed with the display panel 110, the thickness of the panel unit 100may be reduced and flexibility may be increased.

The display panel 110 may include pixels (for example, pixels PXL ofFIG. 3 ) disposed in a display area DA (see FIG. 3 ). The display panel110 may display an image corresponding to input image data using thepixels.

The touch sensor 120 may include sensor electrodes (for example, sensorelectrodes SSE of FIG. 5 ) disposed in a sensing area SA (see FIG. 5 ).The touch sensor 120 may output the sensing signals that changeaccording to the touch input applied to the panel unit 100. In anembodiment, the touch sensor 120 may be a capacitive touch sensor (forexample, a mutual capacitive touch sensor).

The driving circuit unit 200 may include a display driver 210 and atouch driver 220 (or a driving circuit unit of the touch sensor 120).

The display driver 210 may be electrically connected to the displaypanel 110. The display driver 210 may generate driving signals (forexample, gate signals and/or data signals supplied to the pixels) fordriving the display panel 110, and supply the driving signals to thedisplay panel 110. In an embodiment, the display driver 210 may includea gate driver for generating the gate signals, a data driver forgenerating the data signals, and a timing controller for controlling thegate driver and the data driver.

The touch driver 220 may be electrically connected to the touch sensor120. The touch driver 220 may generate driving signals for driving thetouch sensor 120 (for example, touch driving signals supplied to drivingelectrodes of the touch sensor 120), and supply the driving signals tothe touch sensor 120. The touch driver 220 may receive the sensingsignals output from the touch sensor 120 and detect the touch inputbased on the sensing signals.

The driving circuit unit 200 may further include a power supply unitthat generates driving voltages for driving the panel unit 100 using aninput voltage. For example, the driving circuit unit 200 may furtherinclude a power management integrated circuit (PMIC) 230. The PMIC 230may generate a first pixel voltage (for example, a high-potential pixelvoltage) and a second pixel voltage (for example, a low-potential pixelvoltage) to be supplied to the pixels of the display panel 110 andsupply them to the panel unit 100.

FIG. 3 is a plan view illustrating a display panel 110 according to anembodiment.

Referring to FIGS. 1, 2 and 3 , the display panel 110 according to anembodiment may include a substrate SUB and pixels PXL disposed on thesubstrate SUB. The substrate SUB and the display panel 110 including thesame may be provided in various shapes. For example, the substrate SUBand the display panel 110 may be provided in the form of a plate havinga rectangular shape or other shapes, and may include angled or roundedcorner portions.

In FIG. 3 , as an example, the display panel 110 is shown in the form ofa plate having a rectangular shape. Also, in the display panel 110, ahorizontal direction (for example, a row direction) may be defined as afirst direction DR1, a vertical direction (for example, a columndirection) may be defined as a second direction DR2, and a thicknessdirection (or a height direction) may be defined as a third directionDR3.

The substrate SUB may be a base member for forming the display panel110. For example, the substrate SUB may constitute a base surface of thedisplay panel 110.

The substrate SUB and the display panel 110 including the same mayinclude a display area DA and a non-display area NA. The display area DAmay be an area in which an image is displayed. The non-display area NAmay be an area other than the display area DA.

The pixels PXL may be disposed in the display area DA. In an embodiment,each pixel PXL may be a self-light emitting type pixel including atleast one light emitting element (for example, an organic light emittingdiode).

Signal lines SLI and a power source line PL electrically connected tothe pixels PXL may be disposed in the non-display area NA.

The signal lines SLI may include gate lines and/or data lineselectrically connected to the pixels PXL, respectively, or routing lineselectrically connected to the gate lines and/or data lines.

The power source line PL may include a plurality of power source linesincluding a second power source line PL2. For example, the power sourceline PL may include a first power source line (for example, a firstpower source line PL1 of FIG. 4 ) for supplying a high-potential pixelvoltage to the pixels PXL, and the second power source line PL2 forsupplying a low-potential pixel voltage to the pixels PXL. In FIG. 3 ,only the second power source line PL2 is shown as an example of thepower source lines formed on (or as part of) the display panel 110. Inan embodiment, the second power source line PL2 may be formed in thenon-display area NA to surround the display area DA.

Pads electrically connected to the signal lines SLI and the power sourceline PL may be further disposed in the non-display area NA. The pads maybe provided in a pad area PA and may be electrically connected to acircuit board 201 bonded on the pad area PA.

The circuit board 201 may include at least a portion of the drivingcircuit unit 200 or may be electrically connected to the driving circuitunit 200. For example, the display driver 210, the touch driver 220, andthe PMIC 230 may be mounted on the circuit board 201 or electricallyconnected to the display panel 110 via the circuit board 201.

FIG. 4 is a circuit diagram illustrating a pixel PXL according to anembodiment.

Referring to FIGS. 3 and 4 , the pixel PXL according to an embodimentmay include a pixel circuit PXC and a light emitting element LDelectrically connected between the first power source line PL1 and thesecond power source line PL2. A first pixel voltage (for example, ahigh-potential pixel voltage) VDD may be applied to the first powersource line PL1, and a second pixel voltage (for example, alow-potential pixel voltage) VSS may be applied to the second powersource line PL2.

The pixel circuit PXC may be electrically connected between the firstpower source line PL1 and the light emitting element LD. Also, the pixelcircuit PXC may be electrically connected to at least one gate line GLand data line DL, and may be further selectively connected to a sensingline SENL. For example, the pixel circuit PXC may be electricallyconnected to a first gate line GL1 (for example, a scan line SLconnected to pixels PXL of a corresponding pixel row), a second gateline GL2 (for example, a control line CL connected to the pixels PXL ofthe corresponding pixel row), a data line DL (for example, a data lineDL connected to pixels PXL of a corresponding pixel column), and asensing line SENL (for example, a sensing line SENL connected to thepixels PXL of the corresponding pixel column).

The pixel circuit PXC may include at least one transistor and acapacitor. For example, the pixel circuit PXC may include a firsttransistor M1, a second transistor M2, a third transistor M3, and astorage capacitor Cst.

The first transistor M1 may be electrically connected between the firstpower source line PL1 and a first electrode AE (for example, an anodeelectrode) of the light emitting element LD. A gate electrode of thefirst transistor M1 may be electrically connected to a first node N1.The first transistor M1 may control driving current supplied to thelight emitting element LD in response to a voltage of the first node N1.For example, the first transistor M1 may be a driving transistor thatcontrols the driving current of the pixel PXL.

The second transistor M2 may be electrically connected between the dataline DL and the first node N1. A gate electrode of the second transistorM2 may be electrically connected to the first gate line GL1. The secondtransistor M2 may be turned on when (or in response to) a first gatesignal (for example, a scan signal) of a gate-on voltage (for example, ahigh-level voltage) is supplied from the first gate line GL1 toelectrically connect the data line DL and the first node N1.

For each frame period, a data signal of a corresponding frame may besupplied to the data line DL, and the data signal may be transferred tothe first node N1 through the second transistor M2 turned on during aperiod in which the first gate signal of the gate-on voltage issupplied. For example, the second transistor M2 may be a switchingtransistor for transferring each data signal to inside the pixel PXL.

The storage capacitor Cst may be electrically connected between thefirst node N1 and a second node N2. The second node N2 may be a node towhich the first transistor M1 and the light emitting element LD areconnected. The storage capacitor Cst may be charged with a voltagecorresponding to the data signal supplied to the first node N1.

The third transistor M3 may be electrically connected between the secondnode N2 and the sensing line SENL. A gate electrode of the thirdtransistor M3 may be electrically connected to the second gate line GL2.

The third transistor M3 may be turned on in response to a second gatesignal of the gate-on voltage supplied to the second gate line GL2 totransfer an initialization voltage supplied to the sensing line SENL tothe second node N2, or to transfer a voltage of the second node N2 tothe sensing line SENL. The voltage of the second node N2 sensed throughthe sensing line SENL during a sensing period may be provided to anexternal circuit (for example, a timing controller) and used tocompensate for deterioration and/or characteristic deviation of thepixels PXL.

In FIG. 4 , transistors included in the pixel circuit PXC, for example,the first, second, and third transistors M1, M2, and M3 are all shown asN-type transistors, but embodiments are not limited thereto. Forexample, at least one of the first, second, and third transistors M1,M2, and M3 may be changed to a P-type transistor.

The structure and driving method of the pixel PXL may be variouslychanged according to embodiments. For example, the pixel circuit PXC maybe composed of a pixel circuit having various structures and/or drivingmethods in addition to the embodiment shown in FIG. 4 .

For example, the pixel circuit PXC may not include the third transistorM3. In addition, the pixel circuit PXC may further include other circuitelements, such as a compensation transistor for compensating for athreshold voltage of the first transistor M1, at least oneinitialization transistor for initializing the voltage of the first nodeN1 and/or the second node N2, an emission control transistor forcontrolling a period during which the driving current is supplied to thelight emitting element LD, and/or a boosting capacitor for boosting thevoltage of the first node N1. In another embodiment, when the pixel PXLis a pixel of a passive light emitting display device, the pixel circuitPXC may be omitted.

The light emitting element LD may include the first electrode AE, asecond electrode CE, and a light emitting layer disposed between thefirst electrode AE and the second electrode CE. In an embodiment, thelight emitting element LD may be an organic light emitting diode (OLED)including an organic light emitting layer.

The first electrode AE of the light emitting element LD may beelectrically connected to the first power source line PL1 through thepixel circuit PXC. The second electrode CE of the light emitting elementLD may be electrically connected to the second power source line PL2. Inan embodiment, the first electrode AE of the light emitting element LDmay be the anode electrode, and the second electrode CE of the lightemitting element LD may be a cathode electrode.

When the driving current is supplied from the pixel circuit PXC, thelight emitting element LD may emit light with a luminance correspondingto the driving current. Accordingly, each pixel PXL may emit light witha luminance corresponding to the data signal supplied to the first nodeN1 during each frame period.

FIG. 5 is a plan view illustrating a touch sensor 120 according to anembodiment.

Referring to FIG. 5 , the touch sensor 120 according to an embodimentmay include a base layer BL and the sensor electrodes SSE disposed onthe base layer BL.

The base layer BL may be a base member for forming the touch sensor 120.For example, the base layer BL may constitute a base surface of thetouch sensor 120.

In an embodiment, the touch sensor 120 may be integrally formed with thedisplay panel 110. For example, the touch sensor 120 may be directlyformed on the display panel 110. In this case, the display panel 110 (oran encapsulation layer of the display panel 110) may be the base layerBL of the touch sensor 120.

The base layer BL and the touch sensor 120 including the same mayinclude a sensing area SA and a peripheral area NSA (for example, anon-sensing area). The sensing area SA may be an area in which thesensing signals are output in response to the touch input, and theperipheral area NSA may be an area other than the sensing area SA.

In an embodiment, the sensing area SA may correspond to the display areaDA, and the peripheral area NSA may correspond to the non-display areaNA. For example, the sensing area SA may overlap the display area DA,and the peripheral area NSA may overlap the non-display area NA.

The sensor electrodes SSE may be disposed in the sensing area SA. In anembodiment, the sensor electrodes SSE may include first sensorelectrodes ET1 and second sensor electrodes ET2.

In an embodiment, the first sensor electrodes ET1 and the second sensorelectrodes ET2 may extend in different directions. For example, thefirst sensor electrodes ET1 and the second sensor electrodes ET2 mayextend along the first direction DR1 and the second direction DR2,respectively, and may cross each other.

In an embodiment, each of the sensor electrodes SSE may includeelectrode cells EP (also referred to as electrode units) and connectionportions CP (also referred to as connection patterns). Although theelectrode cells EP are shown in plate-shaped patterns in FIG. 5 ,embodiments are not limited thereto. For example, the electrode cells EPmay be formed in mesh patterns.

In an embodiment, each of the first sensor electrodes ET1 may includefirst electrode cells EP1 and first connection portions CP1. The firstelectrode cells EP1 may be arranged (e.g., spaced apart from oneanother) along the first direction DR1. The first connection portionsCP1 may connect adjacent first electrode cells EP1. The first connectionportions CP1 may be integrally formed with the first electrode cells EP1or may be formed of bridge-shaped conductive patterns.

In an embodiment, each of the second sensor electrodes ET2 may includesecond electrode cells EP2 and second connection portions CP2. Thesecond electrode cells EP2 may be arranged along the second directionDR2. The second connection portions CP2 may connect the second electrodecells EP2. The second connection portions CP2 may be integrally formedwith the second electrode cells EP2 or may be formed of bridge-shapedconductive patterns.

The configuration, structure, shape, size, and/or position of the sensorelectrodes SSE may be variously changed according to embodiments. Inaddition, the sensor electrodes SSE may include at least one conductivematerial, and the material constituting the sensor electrodes SSE is notparticularly limited.

In a case that the touch sensor 120 according to an embodiment is amutual capacitance type touch sensor, one group of electrodes among thefirst sensor electrodes ET1 and the second sensor electrodes ET2 may bedriving electrodes of the touch sensor 120, and the remaining group ofelectrodes may be sensing electrodes of the touch sensor 120. Forexample, the first sensor electrodes ET1 may be the driving electrodesof the touch sensor 120 (for example, Tx electrodes receiving a touchdriving signal from the touch driver 220 during the sensing period inwhich the touch sensor 120 is activated), and the second sensorelectrodes ET2 may be the sensing electrodes of the touch sensor 120(for example, Rx electrodes outputting a sensing signal corresponding tothe touch input to the touch driver 220 during the sensing period inwhich the touch sensor 120 is activated).

In an embodiment, the touch sensor 120 may further include dummypatterns DMP. For example, the touch sensor 120 may include the dummypatterns DMP disposed on an edge of the sensing area SA and floated.

Touch lines TLI electrically connected to the sensor electrodes SSE maybe disposed in the peripheral area NSA. Each of the touch lines TLI maybe electrically connected to any one sensor electrode SSE (for example,any one of the first sensor electrode ET1 or the second sensor electrodeET2).

Pads TP electrically connected to the touch lines TLI may be furtherdisposed in the peripheral area NSA. The touch sensor 120 may beelectrically connected to the touch driver 220 through the pads TP.

FIG. 6 is a cross-sectional view illustrating the panel unit 100 of thedisplay device 10 according to an embodiment. For example, FIG. 6schematically shows a cross-section of the panel unit 100 centered onpixel areas PXA in which two pixels PXL including the light emittingelement LD (for example, the organic light emitting diode OLED) aredisposed as in the embodiment of FIG. 4 . Each pixel area PXA mayinclude an area in which circuit elements and/or the light emittingelement LD constituting a corresponding pixel PXL are disposed.

Referring to FIGS. 1 to 6 , the panel unit 100 may include the displaypanel 110, the touch sensor 120, and the protective layer 130sequentially arranged along the third direction DR3.

The display panel 110 may include the substrate SUB, and a pixel circuitlayer PCL, a light emitting element layer LDL, and an encapsulationlayer ENL sequentially disposed on the substrate SUB. The substrate SUBmay constitute the base layer BSL of the panel unit 100.

The pixel circuit layer PCL may include the circuit elementsconstituting the pixel circuit PXC of each of the pixels PXL, and thesignal lines SLI and power source lines PL electrically connected to thepixels PXL. In FIG. 6 , as an example of the circuit elements that maybe disposed in the pixel circuit layer PCL, a transistor M (for example,the first transistor M1 of FIG. 4 ) electrically connected to the lightemitting element LD through contact hole CH and/or first bridge patternBRP1 is shown.

The pixel circuit layer PCL may further include insulating layers. Forexample, the pixel circuit layer PCL may include a buffer layer BFL, agate insulating layer GI, a first interlayer insulating layer ILD1, asecond interlayer insulating layer ILD2, and/or a passivation layer PSV.

The buffer layer BFL may be disposed on the substrate SUB. The bufferlayer BFL may prevent impurities from diffusing into each circuitelement.

A semiconductor layer may be disposed on the buffer layer BFL. Thesemiconductor layer may include a semiconductor pattern SCP of eachtransistor M. The semiconductor pattern SCP may include a channel regionoverlapping a gate electrode GE of a corresponding transistor M, andfirst and second conductive regions (for example, source and drainregions) disposed on both sides of the channel region.

The gate insulating layer GI may be disposed on the semiconductor layer.In addition, a first conductive layer may be disposed on the gateinsulating layer GI.

The first conductive layer may include a gate electrode GE of eachtransistor M. The first conductive layer may further include oneelectrode of the storage capacitor Cst, at least one line or a portionthereof, and/or a bridge pattern.

The first interlayer insulating layer ILD1 may be disposed on the firstconductive layer. In addition, a second conductive layer may be disposedon the first interlayer insulating layer ILD1.

The second conductive layer may include first and second transistorelectrodes TE1 and TE2 of each transistor M. Here, the first and secondtransistor electrodes TE1 and TE2 may be source and drain electrodes. Inaddition, the second conductive layer may further include anotherelectrode of the storage capacitor Cst, at least one line or a portionthereof, and/or a bridge pattern.

The second interlayer insulating layer ILD2 may be disposed on thesecond conductive layer. In addition, a third conductive layer may bedisposed on the second interlayer insulating layer ILD2.

The third conductive layer may include at least one bridge patternincluding the first bridge pattern BRP1 for electrically connecting thepixel circuit layer PCL and the light emitting element layer LDL. Inaddition, the third conductive layer may further include at least oneline or a portion thereof.

The first bridge pattern BRP1 may be electrically connected to the firstelectrode AE of the light emitting element LD of the corresponding pixelPXL through the contact hole CH. Also, the first bridge pattern BRP1 maybe electrically connected to at least one circuit element (for example,the first transistor M1 of FIG. 4 ) constituting the pixel circuit PXCof the corresponding pixel PXL.

The passivation layer PSV may be disposed on the third conductive layer.In addition, the light emitting element layer LDL may be disposed on thepixel circuit layer PCL including the passivation layer PSV.

The light emitting element layer LDL may include light emitting elementsLD of the pixels PXL. Also, the light emitting element layer LDL mayfurther include an insulating layer and/or an insulating pattern (forexample, a pixel defining layer PDL) disposed around the light emittingelements LD.

In an embodiment, in a case that the light emitting element LD of thepixel PXL is an organic light emitting diode OLED, the light emittingelement layer LDL may include the organic light emitting diode OLEDformed in each pixel area PXA. The light emitting element LD may includea first electrode AE, a second electrode CE, and a light emitting layerEML disposed between the first electrode AE and the second electrode CE.Hereinafter, the first electrode AE of the light emitting element LD maybe referred to as a first pixel electrode AE, and the second electrodeCE of the light emitting element LD may be referred to as a second pixelelectrode CE.

Any one of the first pixel electrode AE and the second pixel electrodeCE may be the anode electrode of the light emitting element LD, and theother may be the cathode electrode of the light emitting element LD. Forexample, the first pixel electrode AE may be the anode electrode of thelight emitting element LD, and the second pixel electrode CE may be thecathode electrode of the light emitting element LD.

The first pixel electrode AE may be electrically connected to thecircuit element of the pixel circuit layer PCL (for example, thetransistor M1 of FIG. 4 ) through the contact hole CH passing throughthe passivation layer PSV and/or the first bridge pattern BRP1.

The light emitting element layer LDL may further include the pixeldefining layer PDL disposed between the pixel areas PXA. The pixeldefining layer PDL may include an opening exposing at least a portion ofthe first pixel electrode AE of each of the pixels PXL. In anembodiment, the pixel defining layer PDL may be an organic insulatinglayer including an organic material.

The light emitting layer EML may be disposed in an area corresponding tothe opening of the pixel defining layer PDL. For example, the lightemitting layer EML may be disposed on one surface of the exposed portionof the first pixel electrode AE. In an embodiment, the light emittinglayer EML may have a multi-layered thin film structure including a lightgeneration layer. For example, the light emitting layer EML may includea hole injection layer, a hole transport layer, a light generationlayer, a hole blocking layer, an electron transport layer, and/or anelectron injection layer.

The light generation layer may be independently formed in each pixelarea PXA (for example, a light emitting area of each pixel PXL), and thehole injection layer, the hole transport layer, the hole blocking layer,the electron transport layer, and the electron injection layer may becommon layers connected to each other in light emitting areas adjacentto each other. FIG. 6 shows the light emitting layer EML based on thelight generation layer.

The second pixel electrode CE may be provided and/or formed on the lightemitting layer EML. In an embodiment, the second pixel electrode CE maybe a common electrode commonly provided to the pixels PXL. For example,the second pixel electrode CE may be a plate-shaped electrode formed inthe entire display area DA, and the light emitting elements LD of thepixels PXL may be commonly connected to one second pixel electrode CE.

The encapsulation layer ENL may be disposed and/or formed on the lightemitting element layer LDL including the light emitting elements LD ofthe pixels PXL.

The encapsulation layer ENL may be formed of a single layer or multiplelayers. In an embodiment, the encapsulation layer ENL may include aplurality of insulating layers covering the light emitting element layerLDL. For example, the encapsulation layer ENL may include a firstencapsulation layer ENL1, a second encapsulation layer ENL2, and a thirdencapsulation layer ENL3 sequentially disposed on the light emittingelement layer LDL. In an embodiment, the first encapsulation layer ENL1and the third encapsulation layer ENL3 may be inorganic insulatinglayers, and the second encapsulation layer ENL2 may be an organicinsulating layer. The material and/or structure of the encapsulationlayer ENL may be changed according to embodiments.

The touch sensor 120 (also referred to as a sensor layer or the sensorunit) may include the sensor electrodes SSE disposed on the displaypanel 110. In an embodiment, the sensor electrodes SSE may include thefirst sensor electrodes ET1 and the second sensor electrodes ET2crossing each other as shown in FIG. 5 , and a first insulating layerINS1 may be disposed at intersections of the first sensor electrodesET2ET1 and the second sensor electrodes ET2. In an embodiment, the firstinsulating layer INS1 may be formed on the entire sensing area SA, andmay include contact holes for electrically connecting each of the firstconnection portions CP1 (or each of the second connection portions CP2)to each of the first electrode cells EP1 (or each of the secondelectrode cells EP2). In another embodiment, the first insulating layerINS1 may be an island-shaped insulating pattern(s) independentlydisposed at the intersections of the first sensor electrodes ET1 and thesecond sensor electrodes ET2 (for example, intersections of the firstconnection portions CP1 and the second connection portions CP2).

The protective layer 130 may be disposed on the touch sensor 120. Forexample, the protective layer 130 may be formed over the entire sensingarea SA to overlap the sensor electrodes SSE. The protective layer 130may also be formed on at least a portion of the peripheral area NSA. Theprotective layer 130 may include at least one insulating layer includinga second insulating layer INS2.

In an embodiment, the panel unit 100 may further include at least one ofa color filter layer and/or a color conversion layer. The color filterlayer may overlap each of the light emitting elements LD of the pixelsPXL and may include color filters of the color corresponding to each ofthe pixels PXL. The color conversion layer may include color conversionpatterns overlapping the light emitting elements LD provided in at leastsome of the pixels PXL and including wavelength conversion particles(for example, quantum dots) of the color corresponding to each of the atleast some of the pixels PXL. In an embodiment, the color conversionlayer may further include light scattering particles for increasinglight efficiency of the pixels PXL.

FIG. 7 is a cross-sectional view schematically illustrating anarrangement structure of a second pixel electrode CE of the displaypanel 110 and sensor electrodes SSE of the touch sensor 120 according toan embodiment.

Referring to FIGS. 1 to 7 , the second pixel electrode CE and the sensorelectrodes SSE may be disposed to overlap each other. For example, thesecond pixel electrode CE and the sensor electrodes SSE may be spacedapart from each other with the encapsulation layer ENL of the displaypanel 110 interposed therebetween, and may overlap each other in thedisplay area DA and the sensing area SA.

A parasitic capacitance may be generated between the second pixelelectrode CE and the sensor electrodes SSE, and the parasiticcapacitance may affect the sensing signals output from the touch sensor120. For example, noise may be included in the sensing signals due tothe parasitic capacitance formed between the electrode cells EP of thesensor electrodes SSE and the second pixel electrode CE. The magnitudeand/or aspect of the noise included in the sensing signals may varyaccording to electrical characteristics of the second pixel electrode CE(for example, an impedance value of the second pixel electrode CE). Asthe second pixel electrode CE and the sensor electrodes SSE are disposedcloser together, the influence of the second pixel electrode CE on thesensing signals of the touch sensor 120 may increase.

FIG. 8 is a diagram illustrating the display device 10 centered on thetouch sensor 120 according to an embodiment. For instance, FIG. 8 showsan equivalent circuit of the panel unit 100 centered on a pair of firstand second sensor electrodes ET1 and ET2. For example, FIG. 8 shows amutual capacitance Cm formed between the pair of first and second sensorelectrodes ET1 and ET2 in the touch sensor 120. A method of driving thetouch sensor 120 will be described centered on the mutual capacitanceCm. In addition, FIG. 8 shows a touch driving circuit 222 (for example,a Tx circuit) and a sensing circuit 224 (for example, an Rx circuit)electrically connected to the touch sensor 120.

FIG. 9 is a graph illustrating a sensing signal Sse generated by amutual capacitance Cm of the touch sensor 120, a noise signal Snogenerated by the second pixel electrode CE, and a sensing signal Sse′input to a sensing circuit 224 according to an embodiment.

First, referring to FIGS. 1 to 8 , the touch sensor 120 may include atleast a pair of the first sensor electrode ET1 and the second sensorelectrode ET2 that form the mutual capacitance Cm. The first sensorelectrode ET1 may be electrically connected to the touch driving circuit222, and the second sensor electrode ET2 may be electrically connectedto the sensing circuit 224. In an embodiment, the touch driving circuit222 and the sensing circuit 224 may be integrated together within thetouch driver 220.

A method of driving the touch sensor 120 according to an embodiment willbe described later. During a period in which the touch sensor 120 isactivated, a touch driving signal Sdr may be supplied from the touchdriving circuit 222 to the first sensor electrode ET1. In an embodiment,the touch driving signal Sdr may be an alternating current (AC) signal.When the touch sensor 120 includes a plurality of first sensorelectrodes ET1, the touch driving circuit 222 may sequentially supplythe touch driving signal Sdr to the first sensor electrodes ET1.

When the touch driving signal Sdr is supplied to the first sensorelectrode ET1, the sensing signal Sse corresponding to the touch drivingsignal Sdr may be output through the second sensor electrode ET2 inwhich the mutual capacitance Cm is formed between the first sensorelectrode ET1 and the second sensor electrode ET2. The sensing signalSse may be input to the sensing circuit 224 and used to detect the touchinput. The noise signal Sno may also be input to the sensing circuit 224together with the sensing signal Sse by the mutual capacitance Cm. Whenthe touch sensor 120 includes a plurality of second sensor electrodesET2, the sensing circuit 224 may include a plurality of sensing channels(for example, Rx channels including receivers 224A) electricallyconnected to each of the second sensor electrodes ET2. The sensingcircuit 224 may receive sensing signals Sse′ (for example, signalsincluding the sensing signal Sse by the mutual capacitance Cm and thenoise signal Sno) from the touch sensor 120 through the sensingchannels.

The sensing circuit 224 may amplify, convert, and signal-process thesensing signals Sse′ input from the second sensor electrodes ET2, anddetect the touch input according to the result. To this end, the sensingcircuit 224 may include the receivers 224A electrically connected to thesecond sensor electrodes ET2, at least one analog-to-digital converter224B (hereinafter referred to as “ADC”) connected to the receivers 224A,and a processor 224C.

Each of the receivers 224A may be an analog front end (hereinafterreferred to as “AFE”) that receives the sensing signal Sse′ (forexample, the sensing signal Sse′ including the noise signal Sno) fromthe second sensor electrode ET2 connected thereto. In an embodiment,each receiver 224A may be configured as an AFE including an amplifierAMP, such as an operational amplifier (OPA).

According to an embodiment, a first input terminal IN1 (for example, aninverting input terminal) of the amplifier AMP may be electricallyconnected to a corresponding second sensor electrode ET2, and a secondinput terminal IN2 (for example, a non-inverting input terminal) of theamplifier AMP may be connected to a reference voltage source such as aground voltage source GND. In this case, each receiver 224A may amplifyand output the sensing signal Sse′ input to the first input terminal IN1based on the potential of the second input terminal IN2. For instance,each receiver 224A may receive the sensing signal Sse′ from the secondsensor electrode ET2 through the first input terminal IN1, and mayamplify the sensing signal Sse′ by amplifying and outputting a signalcorresponding to a difference between a voltage of the first inputterminal IN1 and a voltage of the second input terminals IN2.

In an embodiment, the amplifier AMP may be implemented as an integrator.In this case, a capacitor Camp and a reset switch SW may be connected inparallel between the first input terminal IN1 and an output terminalOUT1 of the amplifier AMP.

The ADC 224B may convert an analog signal input from each receiver 224Ainto a digital signal.

The processor 224C may signal-process the digital signal converted bythe ADC 224B, and may detect the touch input according to the signalprocessing result. For example, the processor 224C may detect whether atouch input has occurred and a location thereof by synthesizing signals(amplified and digitally converted sensing signal Sse′) input from thesecond sensor electrodes ET2 via each of the receivers 224A and theADC(s) 224B.

In an embodiment, the processor 224C may be a microprocessor (MPU). Inanother embodiment, the processor 224C may be another type of processor,such as a microcontroller (MCU).

As described above, the touch sensor 120 may output the sensing signalsSse′ of a waveform corresponding to touch driving signals Sdr. Aparasitic capacitance may be formed between the touch sensor 120 and thedisplay panel 110. Accordingly, noise signals Sno may be added tosensing signals Sse according to the mutual capacitance Cm of the touchsensor 120 and input to the sensing circuit 224. Accordingly, an inputsignal of the sensing circuit 224 (for example, the sensing signal Sse′input to the sensing circuit 224) may be distorted.

For example, a first parasitic capacitance Cp1 may be generated betweenthe touch sensor 120 and the second pixel electrode CE. Accordingly,some of charges flowing from the touch driving circuit 222 to the touchsensor 120 may move to the second pixel electrode CE.

Some of the charges that have moved to the second pixel electrode CE maybe retransmitted to the second sensor electrode ET2 through the secondpixel electrode CE and the first parasitic capacitance Cp1, and may beinput to the sensing circuit 224 by being added to the sensing signalSse by the mutual capacitance Cm. Accordingly, the sensing signal Sse′in a form in which the noise signal Sno is added to the sensing signalSse by the mutual capacitance Cm of the touch sensor 120 may be input tothe sensing circuit 224. For example, as shown in FIG. 9 , the amount ofcharges of the sensing signal Sse′ input to the sensing circuit 224 (ora voltage of the sensing signal Sse′ corresponding thereto) may have avalue obtained by adding the amount of charges of the noise signal Snogenerated by the second pixel electrode CE (or a voltage of the noisesignal Sno corresponding thereto) to the amount of charges correspondingto the sensing signal Sse by the mutual capacitance of the touch sensor120 (or a voltage of the sensing signal Sse corresponding thereto).

Another portion of the charges that have moved to the second pixelelectrode CE may be moved to a second parasitic capacitance Cp2 formedby the second pixel electrode CE (for example, a parasitic capacitanceformed between a shielding electrode of a display module (for example, amodule including the display device 10) connected to the referencevoltage source, such as the ground voltage source GND, and the secondpixel electrode CE), or a stabilization capacitor Cs electricallyconnected to the second pixel electrode CE.

In FIG. 8 , a dotted arrow schematically indicates a flow of the chargesmoving to the second pixel electrode CE. With respect to referencenumerals not described in FIG. 8 , the reference numeral Rtxequivalently denotes the resistance of the first sensor electrode ET1and/or a touch line TLI connected to the first sensor electrode ET1, andthe reference numeral Rrx equivalently denotes the resistance of thesecond sensor electrode ET2 and/or a touch line TLI connected to thesecond sensor electrode ET2. The reference numeral Rce equivalentlydenotes the resistance of the second pixel electrode CE, and thereference numeral Rp1 equivalently denotes the resistance of the secondpower source line PL2.

The magnitude and/or waveform of the noise signal Sno generated by thesecond pixel electrode CE may vary according to electricalcharacteristics of the second pixel electrode CE. For example, themagnitude and/or waveform of the noise signal Sno may be changedaccording to the impedance value of the second pixel electrode CE and/orthe second power source line PL2 connected to the second pixel electrodeCE.

Accordingly, according to the impedance value of the second pixelelectrode CE, a value of the sensing signal generated and/or output fromthe sensing circuit 224 (for example, a digital code value correspondingto the capacitance converted by the ADC 224B) may be changed.

FIG. 10 is a diagram illustrating the display device 10 including afirst type of defect in relation to the second pixel electrode CE. InFIG. 10 , as shown in FIG. 8 , the display device 10 according to anembodiment is shown centered on the touch sensor 120. FIG. 11 is adiagram illustrating the panel unit 100 including a second type ofdefect in relation to the second pixel electrode CE. FIG. 12 is adiagram illustrating the panel unit 100 including a third type of defectin relation to the second pixel electrode CE.

Referring to FIGS. 1 to 10 , the stabilization capacitor Cs to beelectrically connected to an output terminal of the PMIC 230 and thesecond power source line PL2 may be separated from the second powersource line PL2. For example, during a manufacturing process of thedisplay device 10 including a module process and an inspection process,the connection between the stabilization capacitor Cs and the secondpower source line PL2 may be disconnected. As the stabilizationcapacitor Cs is separated from the second power source line PL2,impedance values of the second pixel electrode CE and the second powersource line PL2 connected thereto may vary. Accordingly, the amount ofcharges retransmitted from the second pixel electrode CE to the secondsensor electrode ET2 may increase, and thus, the performance of thetouch sensor 120 may be deteriorated.

Referring to FIGS. 1 to 12 , due to a film formation defect of thesecond pixel electrode CE, the impedance values of the second pixelelectrode CE and the second power source line PL2 connected thereto mayvary. For example, the amount of charges retransmitted from the secondpixel electrode CE to the second sensor electrode ET2 may increase, andthus, the performance of the touch sensor 120 may be deteriorated.

For example, as shown in FIG. 11 , when the thickness of the secondpixel electrode CE is changed, a resistance value of the second pixelelectrode CE may be changed, and the distance between the second pixelelectrode CE and the touch sensor 120 may be changed. Accordingly, avalue of the first parasitic capacitance Cp1 may be changed such thatthe level and/or waveform of the sensing signal Sse′ input to thesensing circuit 224 may be changed. Also, when the resistance value ofthe second pixel electrode CE increases, image quality may deterioratedue to a voltage drop of the second pixel voltage VSS.

Alternatively, in some display devices 10, as shown in FIG. 12 , thesecond pixel electrode CE may not be formed in a portion of the displayarea DA due to a film formation defect of the second pixel electrode CEthat may occur in a process of forming the second pixel electrode CE.For example, due to a shift of a mask in a photolithography process, thesecond pixel electrode CE may not be formed in an edge area of thedisplay area DA.

In this case, in an area where the second pixel electrode CE is notformed, display noise may be introduced from the display panel 110 tothe touch sensor 120. Accordingly, the level and/or waveform of thesensing signal Sse′ input to the sensing circuit 224 may be changed. Forexample, a larger display noise may be introduced into the second sensorelectrodes ET2 at a position corresponding to the area where the secondpixel electrode CE is not formed such that a higher level noise signalSno may be included in the sensing signals Sse′ input to the receivers224A of the RX channels connected to the second sensor electrodes ET2.Accordingly, the performance of the touch sensor 120 may bedeteriorated.

FIG. 13 is a diagram illustrating an inspection apparatus 2 of thedisplay device 10 according to an embodiment. For example, FIG. 13 showsthe inspection apparatus 2 electrically connected to a display module 1including the display device 10 (or a sample display device of the samemodel as the display device 10) according to an embodiment and used toinspect a defect of the display device 10. FIG. 14 is a graphillustrating capacitance values of the sensing signals output from thetouch sensor 120 of the display device 10. For example, FIG. 14 shows acode value of the capacitance output from the ADC 224B provided to eachof reception channels Rx_CH connected to the second sensor electrodesET2 (for example, Rx channels of the sensing circuit 224 of the displaydevice 10 or a monitoring apparatus of the inspection apparatus 2).

Referring to FIGS. 1 to 13 , the inspection apparatus 2 according to anembodiment may include a power source generator 22 (also referred to asa power generator or a power voltage generator) and a variable impedancecircuit 24. In an embodiment, the inspection apparatus 2 may be aninspection jig having a printed circuit board shape.

The power source generator 22 may generate a pixel voltage to drive thedisplay device 10. For example, the power source generator 22 mayinclude a power source generating circuit for generating the secondpixel voltage VSS (for example, a direct current (DC)-DC converter (alsoreferred to as a DC-DC (VSS)) for generating the second pixel voltageVSS). In an embodiment, the power source generator 22 may furtherinclude a power source generating circuit for generating the first pixelvoltage VDD. The power source generator 22 may output the second pixelvoltage VSS through an output terminal OUT2.

The variable impedance circuit 24 may be electrically connected to theoutput terminal OUT2 of the power source generator 22. In an embodiment,the variable impedance circuit 24 may include a variable resistancecircuit 24A and a variable capacitor circuit 24B.

The variable resistance circuit 24A may be electrically connectedbetween the output terminal OUT2 of the power source generator 22 and anoutput terminal OUT3 of the variable impedance circuit 24 (for example,a second pixel voltage output terminal of the inspection apparatus 2).

The variable resistance circuit 24A may include resistors R1 to Rkelectrically connected to the output terminal OUT2 of the power sourcegenerator 22 and connected in parallel to each other, first switchesSW11 to SW1 k connected in parallel between the resistors R1 to Rk andthe output terminal OUT3 of the variable impedance circuit 24, and asecond switch SW2 electrically connected between the output terminalOUT2 of the power source generator 22 and the output terminal OUT3 ofthe variable impedance circuit 24.

In an embodiment, each of the first switches SW11 to SW1 k may beconnected in series to any one of the resistors R1 to Rk. The secondswitch SW2 may be connected in parallel with the resistors R1 to Rk andthe first switches SW11 to SW1 k. For example, the second switch SW2 maybe directly connected to the output terminal OUT2 of the power sourcegenerator 22 and the output terminal OUT3 of the variable impedancecircuit 24. In an embodiment, during an inspection to check the imagequality of the display device 10, the impedance of the second pixelelectrode CE may be lowered by turning off the first switches SW11 toSW1 k and turning on the second switch SW2. Accordingly, deteriorationof the image quality due to the variable impedance circuit 24 can beprevented.

By controlling the first switches SW11 to SW1 k and the second switchSW2, a resistance value of the variable resistance circuit 24A may bevariously changed.

The variable capacitor circuit 24B may include third switches SW31 toSW3 j electrically connected to the output terminal OUT2 of the powersource generator 22 and connected in parallel to each other, andcapacitors C1 to Cj connected in parallel between the third switchesSW31 to SW3 j and the reference voltage source (for example, the groundvoltage source GND). In an embodiment, each of the capacitors C1 to Cjmay be connected in series to any one of the third switches SW31 to SW3j.

By controlling the third switches SW31 to SW3 j, a capacitance value ofthe variable capacitor circuit 24B may be variously changed.

During the inspection of the display device 10, the second pixel voltageVSS may be supplied from the power source generator 22 of the inspectionapparatus 2 to the second pixel electrode CE of the display device 10via the variable impedance circuit 24. For example, the output terminalOUT3 of the variable impedance circuit 24 may be electrically connectedto the second power source line PL2 (or a power source pad connected tothe second power source line PL2) of the display device 10. Accordingly,the impedance value of the second pixel electrode CE may be adjusted bythe variable impedance circuit 24 during the inspection of the displaydevice 10.

In an embodiment, a defect related to the second pixel electrode CE ofthe display device 10 may be detected using the inspection apparatus 2including the variable impedance circuit 24. For example, when a defectrelated to the second pixel electrode CE occurs in the display device 10to be inspected, the impedance value of the second pixel electrode CEmay be adjusted using the variable impedance circuit 24 so that thesensing signal Sse′ input to the sensing circuit 224 can besignificantly changed by the noise signal Sno enough to detect thedefect. For example, in each display device 10, the impedance value ofthe second pixel electrode CE may be adjusted using the variableimpedance circuit 24 to be optimized to detect a desired type of defectin relation to the second pixel electrode CE. In this case, an impedancevalue of the variable impedance circuit 24 may be a value experimentallyderived using a sample display device of the same model as the displaydevice 10 before the display device 10 is inspected.

For example, with respect to a sample display device including a desiredtype of defect in relation to the second pixel electrode CE (forexample, the display device 10 in which the stabilization capacitor Csis separated as shown in FIG. 10 , the display device 10 including thepanel unit 100 in which the thickness of the second pixel electrode CEis defective as shown in FIG. 11 , or the display device 10 includingthe panel unit 100 in which a film formation defect of the second pixelelectrode CE occurs as shown in FIG. 12 ), an output signal of the ADC224B (or a monitoring device provided in the inspection apparatus 2 andconnected to the touch sensor 120) may be monitored while changing theimpedance value of the second pixel electrode CE using the variableimpedance circuit 24. In this case, when a capacitance value output fromthe ADC 224B of the sample display device differs from a capacitancevalue output from the ADC 224B of a normal display device by more than areference value under the same impedance condition, the resistance valueand the capacitance value of the variable impedance circuit 24 may beclassified as values capable of detecting defects with respect to thedisplay device 10 of a corresponding model.

For example, when the capacitance value shown by the solid line in FIG.14 is a capacitance value obtained by amplifying and digitallyconverting the sensing signal Sse′ output from the touch sensor 120 of anormal sample display device with respect to a first set value of thevariable impedance circuit 24 (for example, values obtained byamplifying and digitally converting the sensing signals Sse′ output fromthe reception channels Rx_CH connected to the second sensor electrodesET2, and may be different depending on positions of the second sensorelectrodes ET2), and when the capacitance value shown by the dotted linein FIG. 14 is a capacitance value obtained by amplifying and digitallyconverting the sensing signal Sse′ output from the touch sensor 120 of asample display device including a first type of defect in relation tothe second pixel electrode CE with respect to the first set value of thevariable impedance circuit 24, when capacitance values detected from thenormal sample display device and the sample display device including thefirst type of defect show a difference greater than or equal to thereference value, the first set value of the variable impedance circuit24 may be defined as a value capable of detecting the display device 10including the first type of defect. In this way, while variouslychanging the resistance value and the capacitance value of the variableimpedance circuit 24, a set value of the variable impedance circuit 24suitable for detecting a desired type of defect in the display device 10of each model can be extracted, and the extracted set value may bestored in the form of a lookup table according to the resistance valueand the capacitance value of the variable impedance circuit 24. Forexample, as shown in Table 1 below, while changing the resistance valueand the capacitance value of the variable impedance circuit 24 withrespect to the sample display device of each model, a lookup table LUThaving the form shown in Table 1 below can be generated.

TABLE 1 LUT CV1 CV2 . . . CVq RV1 O O . . . O RV2 O O . . . O . . . . .. . . . . . . . . . RVp O O . . . X

In Table 1, CV1 to CVq may represent capacitance values of the variableimpedance circuit 24, and RV1 to RVp may represent resistance values ofthe variable impedance circuit 24. In addition, “O” may indicate a casein which a desired type of defect can be detected in relation to thesecond pixel electrode CE, and “X” may indicate a case in which adesired type of defect is difficult to detect in relation to the secondpixel electrode CE.

When inspecting the display device 10 corresponding to each model, in astate in which the impedance value of the variable impedance circuit 24is set with reference to the lookup table LUT corresponding to themodel, the inspection apparatus 2 may supply the second pixel voltageVSS to the second pixel electrode CE. In addition, the touch sensor 120may be driven, and the capacitance value detected by the touch driver220 (or the monitoring device of the inspection apparatus 2) may becompared with reference data (for example, data corresponding to thecapacitance value corresponding to the normal or defective case of FIG.14 ) stored in advance with respect to the sample display device todetect the defect related to the second pixel electrode CE of thedisplay device 10.

In an embodiment, when it is difficult to directly check the capacitancevalue detected by the sensing circuit 224 of the display module 1including each display device 10 or each sample display device, themonitoring device capable of directly detecting and/or converting andmonitoring the sensing signals (for example, the sensing signals Sse′including the sensing signal Sse by the mutual capacitance Cm and thenoise signal Sno added to the sensing signal Sse) output from the secondsensor electrodes ET2 may be provided or formed in the inspectionapparatus 2.

FIG. 15 is a flowchart illustrating a method of inspecting a displaydevice 10 according to an embodiment. FIG. 16 is a flowchartillustrating a method of generating reference data according to anembodiment. The reference data may be used to determine a defect of thedisplay device 10 (also referred to as a target display device) wheninspecting the defect of the display device 10.

Referring to FIGS. 1 to 16 , before inspecting a defect of the secondpixel electrode CE with respect to the target display device 10, avariable impedance value of the inspection apparatus 2 for the model maybe set using a sample display device of the same model as the targetdisplay device 10. For example, the sample display device may beconnected to the inspection apparatus 2, and an impedance value capableof detecting a desired type of defect in relation to the second pixelelectrode CE (for example, an impedance value optimized for acorresponding model) may be derived while changing the impedance valueof the variable impedance circuit 24. The impedance value may be set asthe variable impedance value (the impedance value of the variableimpedance circuit 24) of the inspection apparatus 2 for thecorresponding model (or an inspection for detecting a specific type ofdefect in the corresponding model). (ST10)

In a state in which the impedance value of the variable impedancecircuit 24 is adjusted to the set variable impedance value, thereference data that can be used to inspect a defect of the targetdisplay device 10 may be obtained using the sample display device. Forexample, the impedance value of the variable impedance circuit 24 may beadjusted to the set variable impedance value, and the variable impedancecircuit 24 of the inspection apparatus 2 may be electrically connectedto the second pixel electrode CE of the sample display device to supplythe second pixel voltage VSS to the second pixel electrode CE. Inaddition, the reference data may be obtained based on sensing signalsoutput from the touch sensor 120 of the sample display device. (ST20)

In an embodiment, first reference data corresponding to a non-defectivedisplay device 10 may be obtained using at least one sample displaydevice. Also, reference data corresponding to the display device 10including a specific type of defect in relation to the second pixelelectrode CE may be further obtained using the sample display device.For example, the first reference data may be obtained based on thesensing signals output from the touch sensor 120 of a non-defectivesample display device. (ST21) In addition, second reference data may beobtained based on sensing signals output from the touch sensor 120 ofthe sample display device including a first type of defect in relationto the second pixel electrode CE (for example, a connection defectbetween the second pixel electrode CE and the stabilization capacitorCs, such as separation of the stabilization capacitor Cs, etc.). (ST22)In an embodiment, the second reference data may be obtained based on thesensing signals output from the touch sensor 120 of the sample displaydevice including a second type of defect in relation to the second pixelelectrode CE (for example, a film formation defect of the second pixelelectrode CE). (ST23) When only one type of defect is detected inrelation to the second pixel electrode CE, a step of obtaining thesecond or third reference data may be omitted.

Thereafter, the variable impedance value of the inspection apparatus 2may be adjusted according to the target display device (for example,according to the model of the target display device), and the targetdisplay device may be connected to the inspection apparatus 2. (ST30)

Thereafter, the power source generator 22 of the inspection apparatus 2may be driven, and the second pixel voltage VSS may be supplied to thesecond pixel electrode CE of the target display device 10 through anoutput terminal connected to the variable impedance circuit 24 (forexample, the output terminal OUT3 of the variable impedance circuit 24).(ST40)

In a state in which the second pixel electrode CE of the target displaydevice 10 is electrically connected to the variable impedance circuit24, the touch sensor 120 of the target display device 10 may be driven.(ST50)

Thereafter, based on the sensing signals output from the touch sensor120 of the target display device 10 (for example, capacitance codevalues converted into digital values), a defect related to the secondpixel electrode CE of the target display device 10 may be detected. Forexample, it may be determined whether there is a defect related to thesecond pixel electrode CE by comparing the sensing signals output fromthe touch sensor 120 of the target display device 10 with the firstreference data. In addition, the type of defect related to the secondpixel electrode CE of the target display device 10 may be determined bycomparing the sensing signals output from the touch sensor 120 of thetarget display device 10 with the second reference data and/or the thirdreference data. (ST60)

As described above, according to various embodiments, the impedancevalue of the variable impedance circuit 24 of the inspection apparatus 2connected to the second pixel electrode CE of the target display device10 may be adjusted according to the model of the target display device10 to be inspected, and the defect related to the second pixel electrodeCE of the target display device 10 may be easily or readily detectedbased on the sensing signals output from the touch sensor 120 of thetarget display device 10. In a case that the variable impedance value bythe combination of the resistors R1 to Rk and the capacitors C1 to Cjprovided in the variable impedance circuit 24 of the inspectionapparatus 2 is subdivided, the impedance value of the second pixelelectrode CE may be easily or readily adjusted for various models oftarget display devices 10. Accordingly, usability of the inspectionapparatus 2 may be increased.

According to various embodiments, one or more defects related to a pixelelectrode of a display device may be detected using a variable impedancecircuit provided in an inspection device and a touch sensor of thedisplay device. The effects according to various embodiments, however,are not limited by the contents described above, and various additionalor alternative effects are contemplated.

Although certain embodiments and implementations have been describedherein, other embodiments and modifications will be apparent from thisdescription. Accordingly, the inventive concepts are not limited to suchembodiments, but rather to the broader scope of the accompanying claimsand various obvious modifications and equivalent arrangements as wouldbe apparent to one of ordinary skill in the art.

What is claimed is:
 1. A method for inspecting a display deviceincluding a pixel electrode and a touch sensor overlapping the pixelelectrode, the method comprising: adjusting an impedance value of avariable impedance circuit of an inspection apparatus according to amodel of the display device; driving a power source generator of theinspection apparatus; supplying a pixel voltage to the pixel electrodethrough an output terminal connected to the variable impedance circuit;driving the touch sensor; and detecting a defect related to the pixelelectrode based on sensing signals output from the touch sensor.
 2. Themethod of claim 1, further comprising: setting the impedance value ofthe variable impedance circuit for the model using a sample displaydevice of a same model as the display device, wherein the impedancevalue of the variable impedance circuit is adjusted according to a setimpedance value.
 3. The method of claim 2, wherein setting the impedancevalue of the variable impedance circuit is performed before connectingthe display device to the inspection apparatus.
 4. The method of claim1, further comprising: obtaining first reference data using anon-defective sample display device, wherein detecting the defectrelated to the pixel electrode comprises determining whether the defectrelated to the pixel electrode exists by comparing the sensing signalswith the first reference data.
 5. The method of claim 4, furthercomprising at least one of: obtaining second reference data using asample display device, the sample display device comprising a first typeof defect in relation to the pixel electrode; and obtaining thirdreference data using a sample display device, the sample display devicecomprising a second type of defect in relation to the pixel electrode.6. The method of claim 5, wherein detecting the defect related to thepixel electrode further comprises determining a type of defect relatedto the pixel electrode by comparing the sensing signals with at leastone of the second reference data and the third reference data.
 7. Themethod of claim 6, wherein obtaining at least one of the first referencedata, the second reference data, and the third reference data isperformed before connecting the display device to the inspectionapparatus.
 8. The method of claim 1, wherein the defect related to thepixel electrode comprises at least one of a connection defect betweenthe pixel electrode and a stabilization capacitor, and a film formationdefect of the pixel electrode.
 9. The method of claim 1, wherein thepixel voltage is a low-potential pixel voltage of the display device.10. An apparatus for inspecting a display device, the apparatuscomprising: a power source generator configured to generate a pixelvoltage of the display device; and a variable impedance circuitelectrically connected to an output terminal of the power sourcegenerator, wherein the variable impedance circuit comprises: a variableresistance circuit electrically connected between the output terminal ofthe power source generator and an output terminal of the variableimpedance circuit; and a variable capacitor circuit electricallyconnected between the output terminal of the power source generator anda reference voltage source.
 11. The apparatus of claim 10, wherein thevariable resistance circuit comprises: resistors electrically connectedto the output terminal of the power source generator and connected inparallel with each other; first switches electrically connected inparallel between the resistors and the output terminal of the variableimpedance circuit, each of the first switches being electricallyconnected in series to any one of the resistors; and a second switchelectrically connected between the output terminal of the power sourcegenerator and the output terminal of the variable impedance circuit, thesecond switch being electrically connected in parallel with theresistors and the first switches.
 12. The apparatus of claim 11, whereinthe second switch is directly connected to the output terminal of thepower source generator and the output terminal of the variable impedancecircuit.
 13. The apparatus of claim 10, wherein the variable capacitorcircuit comprises: third switches electrically connected to the outputterminal of the power source generator and electrically connected inparallel to each other; and capacitors electrically connected inparallel between the third switches and the reference voltage source,each of the capacitors being electrically connected in series to any oneof the third switches.
 14. The apparatus of claim 10, wherein the powersource generator is configured to supply the pixel voltage to a pixelelectrode of the display device via the variable impedance circuit. 15.The apparatus of claim 14, wherein the pixel voltage is a low-potentialpixel voltage.